Question: 5 glue sticks cost $4.55. Which equation would help determine the cost of 8 glue sticks?
Explanation: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 5 glue sticks. We want to know the cost of 8 glue sticks. We can write the numbers of glue sticks as a proportion: $\dfrac{5}{8}$ We know 5 glue sticks costs $4.55. We can let $x$ represent the unknown cost of 8 glue sticks. The proportion of these costs can be expressed as: $\dfrac{\$4.55}{x}$ The cost changes along with the number of glue sticks purchased, and so the two proportions are equivalent. $\dfrac{5}{8} = \dfrac{\$4.55}{x}$